Typical American adults carry a number of cards on their persons to identify themselves for various purposes. One very common type of identification card is a payment card such as a credit or debit card. Traditionally, payment cards have carried a magnetic stripe from which a point of sale terminal may read data such as the account number of a payment account to be accessed with the payment card. More recently, it has been increasingly common for payment cards to be embodied as contactless smart cards. Payment cards in this form are able to communicate the payment card account by wireless data transmission to a proximity reader that is part of or is interfaced to the point of sale terminal. The same functionality may be provided in devices—such as key fobs—that are not shaped like a conventional payment card.
For relatively small transactions, it is now often the case that presentation of the payment card/device is all that is required for the transaction to go forward. However, for larger transactions, an additional layer of security may be interposed by requiring the cardholder to provide his/her signature or to enter a personal identification number (PIN).
U.S. Pat. No. 6,957,771, issued to Norris, discloses a wristwatch that may also incorporate functions like those of a contactless smart card payment card. The payment device/wristwatch disclosed in Norris provides enhanced security in that for the device to function it must be authenticated by entry therein of a PIN or by the device detecting a biometric characteristic of the wearer. If configured for authentication by entry of a PIN, the Norris device may retain its authenticated state for a period of time and/or until removed from the wearer's wrist.
One drawback of Norris's device is that it appears to require either a keypad to allow PIN entry or a biometric sensor or both. These requirements would tend to increase the size, cost and complexity of the device.